Anonymous Z

So the story happened when I used an app on facebook, called ask.com. There was an anonymous guy (or I individually think so), who keeps sending me sexual confessions of how many times he masturbated and dreamed of having s** with me. In the beginning, he only sent me sentimental confession, but then he started to describe how and where we would have s**.Worst thing is I have a boyfriend, but I can't help fantasizing and arosuing by only reading those lines. I feel like I started to be attracted so much by this guy, that I feel a weird distance forming between me and my bf when we meet up...
I even dreamed of it. Damn, I hate this, I want to stop, yet, don't know how to .